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New Scientist Live

My lizard persona depends on my neighbours

LIZARDS are famed for a rather extreme escape tactic – they shed their tails to avoid predation. But for Erhard’s wall lizard, found across Greece’s Cyclades islands, its tendency to jettison the tail – and indeed its tolerance for disturbance – depends on which island it lives on.

The Cyclades became isolated from each other more than 11,000 years ago. That stranded each island’s lizards, marooning them alongside different predators. As a result, the lizards, Podarcis erhardii, have been walking different evolutionary paths. Kinsey Brock of the University of Michigan, Ann Arbor, tested the lizards’ fear factor by walking towards 913 individuals from 37 islands plus the mainland. The average lizard ran when Brock got within 1.8 metres, but some let her get to 10 centimetres.

She found a link between the distance at which a lizard flees and the island it hailed from. Lizards from smaller islands with fewer types of predator, or that had been disconnected from mainland predators for longer, let her come far closer compared with their more fearful relatives (Evolution, doi.org/ws7).

In lab tests, Brock also found that lizards from safer islands were less likely to ditch their tails when put under physical pressure through pressing. “If you’re living in a predator-free environment, it would be evolutionarily disadvantageous to spend your time running away while other lizards are foraging and mating,” she says.

This article appeared in print under the headline “On tameness and tail-dropping in island lizards”